Method of forming a carton enclosed package from a preformed foldable blank



R. R. PERDUE METHOD'OF FORMING A CARTON ENCLOSED PACKAGE FROM A PREFORMED FOLDABLE BLANK Filed May 10, 1965 June 11, 1968 United States Patent METHOD OF FORMING A CARTON ENCLOSED PACKAGE FROM A PREFORMED FOLDABLE BLANK Richard R. Perdue, Taylors, S.C., assignor to W. R. Grace & C0., Duncan, S.C., a corporation of Connecticut Filed May 10, 1963, Ser. No. 279,550 4 Claims. (Cl. 53-47) This invention relates to methods and articles useful in the packaging art. More specificaly the invention relates to a preformed, foldable blank used in preparing a carton enclosed thermoplastic film covered product and to a semicontinuous or continuous process for forming the carton enclosed package from such blanks.

In the packaging of various food items such as sliced bacon, dried or dehydrated soups, eggs, coffee, milk and the like there are presently two widely used production methods. One such method involves placing the product (eg bacon slices) on the base portion of a pre-scored paperboard wrapper, folding the wrapper about and locking it in place with clips, adhesives, locking tabs or the like, and then enclosing the carton or box thus formed in a sheet :of transparent heat scalable thermoplastic film, e.g., polyethylene. This method obviously requires an excessively large amount of expensive hand labor and of wrapping film. In another commonly used method the product is packaged in a pounch of flexible transparent film (which may be evacuated or gas flushed and then hermetically sealed) and the pounches thus formed are inserted into a printed paperboard carton for shipment to the wholesaler or retailer. This latter method as presently practice-d requires two separate packaging operations and two separate machines for performing the'same.

It is an object of this invention to provide a novel method for producing carton protected film packages similar to those previously produced, but at a much lower overall cost.

Another object of the invention is to provide a prescored foldable blank especially adapted for use in the new packaging method.

Yet another object is to provide a method for continuous production of a carton protected vacuum or gas flushed film package at high production rates.

Other objects and advantages of the invention will be apparent to those skilled in the art after consideration of the following detailed description, the appended claims and the accompanying drawings.

in the drawings:

FIGURE 1 is a perspective view illustrating schematically the operative steps in the method of this invention, and means for performing the same;

FIGURE 2 is a plan view of a foldable blank constructed in accordance with the invention;

FIGURE 2a is a partial plan view of an alternative blank construction;

FIGURE 3 is a perspective view of the blank of FIG- URE 2 after it has been erected;

FIGURE 4 is an elevational view, in cross section, of the package made in accordance with the teachings of this invention; and

FIGURE 5 is an enlarged sectional view of the encircled portion Vin FIGURE 4.

The blank used in the invention will first be described. As best seen in FIGURE 2, the prescored, unfolded aasmzr Patented .iurne U, 1968 blank comprises a central rectangular base portion it? and a side wall portion 11 extending laterally from each edge of the base. The length of each side wall portion is equal to the length of the base edge from which it extends. Each side wall portion has an equal width b. At the extremity of each side wall there is a flap or flange 12 or 13. All flaps have substantially the same width a. Preferably the length of each of at least one pair of oppositely disposed flanges (e.g. flanges 12) is greater than the length of each of the other pair of oppositely disposed flanges (e.g. 13). This increased length is equal to twice the width (1, one half of which is disposed at each end of the longer flanges. This particular dimensional relationship is required in order to result in an erected blank having a continuous lateral flange at its upper perimeter of essentially equal width, all parts of which are on essentially the same plane. If desired the same result could be achieved by using the construction illustrated in FIG- URE 2a. In this alternative embodiment each end of each flange has a triangular tab 60, each of which is a triangle. The equal legs of the triangle each have a length a and the tabs are positioned so that one of these sides is integral with the end of the flange with which it is associated.

To permit viewing package contents in some packages, c.g. bacon or luncheon meat packages, there preferably is a window aperture. 14- cut through the base portion, usually but not necessarily somewhere in the middle of such portion. The area of this aperture may range up to about percent or so of the total area. of the base portion. The aperture perimeter can have any desired shape and is not restricted to the substantially square configuration illustrated in the drawings. For other types of products, e.g., freeze dehydrated soups and vegetables, dehydrated or ground coffee, etc.; in which event no window is provided in the blank of this invention.

When the packaging method (to be described more fully) utilizes a vacuum forming step, it is desirable to provide further apertures 16 in the base portion of the blank in order to obtain suitable conformation of the vacuum drawn film to the contour of the erected blank.

Score lines 17, 18, 19, 2t) and 21, 22., 23, 24 are provided to assist in erecting the blank into an open-mouthed, flanged, rectangular carton 25 (as shown in FIGURE 3). The flanges 12, 13 of this container are provided with heat activatable adhesive 26 extending completely around the upper perimeter of the container. The adhesive can be applied in known manner either before or after the carton blank is erected.

The best mode now contemplated for carrying out the method of this invention will be described in connection with FIGURE 1, which illustrates schematically the steps involved. Briefly the method comprises setting up the previously described blank in a female mold and, if necessary, applying heat-activatable adhesive to the flanges; heating a thermoforama'ble thermoplastic film to temperatures in the forming range; covering the open mouth of the blank with the heated film thereby activating the aforesaid adhesive; thermoforming the heated film into a substantially conforming liner for the blank; at least partially cooling the subassembly thus formed to set the adhesive and formed film liner; filling the lined blank with product; covering the mouth of the film lined, filled blank with a material that can be heat sealed to the film liner; and finally heat sealing the cover material m th lined blank around the flanges thereof. When the product is a food material preferred (but nevertheless optional) additional steps include evacuating the filled, lined blank before completion of sealing the cover material; or, in lieu of, or in addition to, evacuating, flushing or back filling with an inert or innocuous gas.

FIGURE 1 shows schematically the operations involved in performing the method in a semi-continuous manner, i.e., a manner which, while involving intermittent motion still gives continuous production. In the illustrated embodiment the flow of operations proceeds from left to right.

A blank 25a is fed from a continuous die cut pre-scorcd web 27, severed from the the web and placed into register with each of the female mold forms 29 that are carried on endless driven conveyor 28. Alternatively, individual pre-severed and stacked blanks 250 could be supplied from a suitable holding magazine equipped with a dispenser-indexer device.

In any case, the blank is pressed into conformity with the mold by carton forming plug 31. The plug is suitably shaped so as to erect the blank 75a into a set up carton 25 (as illustrated, e.g. in FIGURE 3) the flanges 12 and 13 of which extend around the upper perimeter of mold 29.

In the event that the flanges have not been pre-coated with adhesive 26, such coating application is performed by adhesive coater 32.

Preparatory to the next step in the operation, a thermoformable thermoplastic film 46 such as polyethylene, polypropylene, polystyrene, etc., is drawn from feed roll 33 over heated roll 34 and then over the top of the mold 29 which now carries set-up blank 25. The temperature of heating roll 34 and the speed of travel of the film over the roll is chosen so as to heat the film to thermoforming temperatures. Preheating the film to these temperatures prior to bringing it over the mold also results in the addi tional function of activating the thermo-activatable adhe sive 26. on the flanges of the erected carton.

The assembly next passes to a thermoforming station where the overlying hot film is formed into conformity with the cavity of the erected carton 25. This may be done by use of any one of the well known thermoforming methods. Preferably the forming is accomplished by vacuum drawing the hot film into the carton cavity by reducing the pressure beneath the female mold cavity via a suitable suction box 35 or other like suitable device. During the vacuum drawing operation the film 46 is held in place over the mouth of the erected carton by holddown device 37, and by tension on the film as it is drawn from feed roll 33. Vacuum is drawn through the erected blank via the window 14 and apertures 16. In the absence of these apertures the vacuum can be drawn through the slits at the corners of the erected blank or through a plurality of performations which may be provided along the score lines 17, 18, 19, and 20 or in the body portion 10 of the blank.

The film-lined blank now passes to a filling station where product to be packaged is inserted into the thermoformed film pocket. Filling can be accomplished manually or mechanically as, e.g., by filling devices such as feed tube 36 or other like known device. As the lined blank travels from the forming station to the filling station it is cooled by ambient atmosphere (or by other suitable means, if desired) to temperatures where the film pocket and the therrno-activatable adhesive become permanently set.

After filling, the assembly moves to a covering and closing station. Here a suitable heat sealable cover material 39 such as heat scalable thermo-plastic film, or paperboard having a heat scalable plastic coating, is drawn from feed roll 38 over the filled carton. Sealing head 41 is lowered over the covered carton and heat seals the cover material to the film liner 46 around the flange perimeter of the erected carton. If desired or necessary for any particular product, the sealing head can, in known manner, be provided with suitable means for evacuating,

gas flushing or otherwise altering the internal atmosphere of the package before the cover is completely sealed. It will be obvious that the covers could be supplied from a stack of pre-severed, individual sections rather than being drawn from a continuous web.

The sealed packages move towards the discharge end of the conveyor in the form of a continuous band. The cover material, if fed in Web form, is severed between molds by cutting device 42 after which the individual separated packages are ejected from the molds 29 and transferred to take off conveyor 43.

Any one of several known drive arrangements can be used to obtain the necessary intermittent motion of conveyor 28 that is required to perform the individual operations that take place at the various stations. Fully continuous operation can be achieved by constructing the apparatus in such manner that the various elements such as the forming plug 31, holddown device 37, sealing head 41, etc. travel with the conveyor for a short distance while performing their function and then reciprocate counter to the conveyor travel direction to begin operation on the next succeeding carton.

The package produced by this invention is illustrated in FIGURES 4 and 5. It will be noted that in normal usage the package is inverted so that cover material 38 forms a supporting base and the erected blank 25 forms a surrounding cover. In the embodiment illustrated the base of the package is comprised of paperboard sheet 49 having coextensive continuous coating 40 of suitable material that is relatively impermeable to gases and moisture vapor. This base is hermetically heat sealed to the thermoformed plastic film liner 46 along the flanges 12 and 13. The periphery of the liner is in turn adhesively sealed to these flanges by adhesive 47. Product 48 e.g., a stack of sliced luncheon meat, is protectively packaged between the liner and base. Carton 51, the sides 52 of which are of approximately same height as height of the product stack, surrounds and partially covers the top of the film enclosed product. Window aperture 53 in the top 54 of the carton permits viewing of product by a prospective purchaser.

The foregoing description is necessarily quite detailed. It will be understood that various modifications may be made in size, shape, sequence of operations, etc. For example it is possible to use adhesives other than those which are heat activatable, e.g., pressure sensitive adhesives. In the latter case the film liner can be secured to the erected blank by the pressure applied in the final sealing step.

It will be obvious that the film liner may comprise a laminate of different thermoformable plastics if desired for any particular purpose. Such laminates include, but are not limited to, those composed of separate bonded layers of polyethylene and a Saran-type polymer, polyethylene and a polyester (such as the polyethylene terephthalate sold commercially under the trade name Mylar), polyethylene and cellophane or any other like combination of thermoplastic materials. Similar considerations apply to the cover material which may if desired be composed of laminate of paperboard, aluminum foil and polyethylene, or paperboard, a saran-type polymer and polyethylene or the like in order to have better moisture barrier properties and lower oxygen permeability.

Those skilled in the art will recognize other equivalent procedures and/or materials.

What is claimed is:

1. A method of forming a sealed package from a carton blank and thermoplastic film comprising the steps of:

(a) pressing a fiat, pre-scored blank into conformity with a female mold so that flanges are formed com pletely around the upper periphery of the mold;

(b) coating the flanges with a heat-activatable adhesive;

(c) heating 'a thermoformable thermoplastic film to forming temperature;

(d) covering the mouth of the mold with the heated 5 6 film so that the film adheres to the adhesive com- 4. The method of claim 1 wherein the cover material pletely around the periphery of the blank; is paperboard and including the step of: (e) thermoiorming the film into a substantially con- (1) coating the paperboard cover material with a heat formrng liner for the blank; scalable thermoplastic resin. (f) filling the lined blank with the product to be pack- 5 aged; References Cited (g) covering the mouth of the filled blank With a heat UNITED STATES PATENTS sealable cover materialand ,j 2,885,840 5/1959 Blackburn 53-22 (hghseahng the cover material to the thermoiormable 10 3,861,984 11/1962 Mahafly 53 22 2. The method of claim 1 wherein the paperboard 2858O13 12/1958 Vmes ct 206-4531 2,948,390 0/1960 Wagaman 206-4531 blank 1s provided with an aperture in 1ts base and the 2 621 129 12/1952 Ramsbottom et a1 mhermoforminfi is achieved bv vacuum drawing. 311242915 3/1964 Ameson X 3. Th6 met 0d Of C 8.1m 1 In Which thfi COVE].- material 3,195,425 7 9 5 Taggart 93 3 01 is fed from 'a continuous web and an amount sufficient 15 3,247,643 4/1966 to cover the mouth of the filled blank 1s severed from the web. TRAVIS S. MCGEHEE, Primary Examiner.

Bartelt 53-l 84 X 

1. A METHOD OF FORMING A SEALED PACKAGE FROM A CARTON BLANK AND THERMOPLASTIC FILM COMPRISING THE STEPS OF: (A) PRESSING A FLAT, PRE-SCORED BLANK INTO CONFORMITY WITH A FEMALE MOLD SO THAT FLANGES ARE FORMED COMPLETELY AROUND THE UPPER PERIPHERY OF THE MOLD; (B) COATING THE FLANGES WITH A HEAT-ACTIVATABLE ADHESIVE; (C) HEATING A THERMOFORMABLE THERMOPLASTIC FILM TO FORMING TEMPERATURE; (D) COVERING THE MOUTH OF THE MOLD WITH THE HEATED FILM SO THAT THE FILM ADHERES TO THE ADHESIVE COMPLETELY AROUND THE PERIPHERY OF THE BLANK; (E) THERMOFORMING THE FILM INTO A SUBSTANTIALLY CONFORMING LINER FOR THE BLANK; (F) FILLING THE LINED BLANK WITH THE PRODUCT TO BE PACKAGED; (G) COVERING THE MOUTH OF THE FILLED BLANK WITH A HEAT SEALABLE COVER MATERIAL; AND, (H) SEALING THE COVER MATERIAL TO THE THERMOFORMABLE FILM. 